Many different types of device are fitted with a radio frequency (RF) antenna, to enable wireless remote communication with the device, for example for configuration of the device or for remote control of the device. For example, near field communication (NFC) enables communication wirelessly and in a non-contact way with a device using a remote communications device.
One example of a type of device which is increasingly being provided with a wireless communications interface is a luminaire or other lighting arrangement. The wireless communication may be used to control the light output.
A near field communication (NFC) system embedded into an LED luminaire or module for example enables easy configuration and reconfiguration of the light output. This is for example implemented by adding an NFC tag integrated circuit (IC) and its associated antenna to the lighting product. The IC has wired internal connections to the embedded master control unit of the product, so that instructions written to the tag IC by a remote NFC transponder may be accessed by the master control unit.
US20030146803A1 discloses a matching network that couples the RF power supply to the RF antenna. The RF power supply is connected to the primary side of a transformer and the antenna is connected electrically at the secondary side of the transformer.
Often, a metal housing and/or heat sink is a part of electrical module. The NFC tag is then integrated with a printed circuit board (PCB) inside the module. The antenna performance, for example as indicated by the maximum reading distance of the antenna of a particular NFC reader, is seriously affected due to these surrounding metal parts.
One usual approach to maintain a large reading distance is to provide ferrite material, such as a ferrite sheet, to isolate the antenna from the surrounding metal parts. However, using an extra ferrite sheet leads to increased material cost. US20070273600A1 discloses a structure that a magnetic member is interposed and arranged between an antenna element and a printed circuit board, and the magnetic member is for demonstrating a high isolation effect between the antenna element and the ground plane of the printed circuit board, thereby enhancing antenna radiation characteristics. US20070273600A1 further discloses a magnetic layer that can be used as an excellent member of a high-frequency magnetic component used in 100 MHz or in a high-frequency domain of 1 GHz or above such as an antenna substrate, a transformer magnetic core, a magnetic head core, an inductor, a choke coil, a filter “or” a wave absorber.